Real-time risk stratification of patients with acute pulmonary embolism by grading the reflux of contrast into the inferior vena cava on computerized tomographic pulmonary angiography

Objective: To investigate whether fast grading of reflux of contrast to the inferior vena cava (IVC) on computerized tomographic pulmonary angiography (CTPA) is a potential biomarker for real-time risk stratification. Methods: We retrospectively identified 343 patients investigated for possible pulmonary embolism (PE) by CTPA at our medical center between September 2004 and March 2006. A total of 145 consecutive patients with PE (age 67 +/- 19 years) and 168 consecutive ones with negative CTPAs (age 64 +/- 20 years) fulfilled entry criteria. CTPAs were evaluated for retrograde reflux of contrast to the IVC by fast visual grading from 1 to 6 using the original axial images. Pulmonary obstruction index, the diameters of right and left ventricles and pulmonary artery, and patient survival data were recorded as well. Results: Twenty-nine (20.0%) patients with positive CTs and 23 (13.7%) patients with negative CTs had substantial degrees (>= 4) of reflux of contrast to the IVC (P = 0.14). The Kaplan-Meier 30-day survival curves demonstrated significant reduction in survival in individuals with PE and grade >= 4 reflux of contrast to the IVC compared with lower grades (P = 0.008), but not in patients with grade >= 4 and no PE on CTPA (P = 0.26). The other cardiovascular parameters showed no significant correlation with survival in patients with and without PE. Conclusion: Substantial grades of reflux of contrast to the IVC during CTPA could predict early mortality in patients with acute PE. Rapid grading of reflux of contrast from the original axial CTPA images can be used for real-time risk stratification in patients with acute PE.